QRM Eliminator

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Expand view Topic review: QRM Eliminator

Re: QRM Eliminator

by M0BVL(Silent Key) » Wed Oct 31, 2018 11:01 pm

Certainly worth the effort

Re: QRM Eliminator

by M0XXQ » Wed Oct 31, 2018 12:17 am

I worked these two lads over in the Republic of Ireland near Donegal, here is another video showing the effect the Phasing Noise Eliminator makes, quite outstanding really.
https://1drv.ms/u/s!Au3guiGeoxqwpLM1YKQ0NFl8wc6klA

Re: QRM Eliminator

by M0VMT » Sun Oct 28, 2018 8:30 pm

Good work Rob......needs a coat of etch primer then some satin black :D
Then we can retail them at £150 :lol:

QRM Eliminator

by M0XXQ » Sun Oct 28, 2018 7:54 pm

Having recently ventured on to the HF bands after lurking on 50 and 70MHz I was quite intrigued with the thought of throwing up a random length of wire and working the world - how wrong was I!
I will keep the antenna story for another article however in big handfuls the design is based on G7FEK Multi-band Marconi design with a elaborate junction box for remotely controlling a relay to switch a large, heavy current loading coil in and out for top band, 160M
operation - a full weekend of hard graft to get it assembled, erected, tested, taken down, re-tested and so on and so forth, you get the picture right?

Anyway, it works great on top band however my noise floor is S9+20dB this any station below this is unintelligible which is very frustrating, in the modern time of "electronic smog" that chokes the electromagnetic spectrum and goes unpunished we as Radio HAM's suffer the worst, as long as brown envelopes are past under the table with big government and corrupt test houses we have no chance - or do we?

My initial thought was to develop a magnetic loop for top band, several turns and around five feet in diameter and a switch box keyed by the radio to change over between the Loop and the Marconi for receive and transmit respectively, but my attention was drawn to something called an X-Phase QRM eliminator which is based on a design that has been kicking around for decades and has appeared in several commercial guises over the years from the likes of WIMO, MFJ and various HAM's around the world including a guy called Terrence VK5TM who adapted the original version which I THINK goes back to G4WMX, GW3DIX and later modified by Hans DK9NL.

So, all credit goes the guys mentioned above and I simply took the design by VK5TM and modified it slightly to fit my application which basically has an additional BC337, BAT85 and 22K resistor and uses 12V coil relays instead of 6V, I re-drew the design in Eagle CAD which I spent a great deal of time laying out a single sided PCB which I will provide at a later date.
Now, I understand that Terry VK5TM has had his designs used for commercial gain without his permission, which to be fair just isn't cricket so before I get into the meat and potatoes of the project I will say that if anyone needs a PCB /Kit please contact Terry VK5TM who has clear instructions for importing his kit to the UK and the correct commodity codes for customs to avoid duty or the other option is to make your own - please don't ask me to build one for you as I simply don't have the time and can't be arsed getting caught up in the whole argy-bargy as to who coped whos design so I am gonna sit this one out lads!

Link to Terry VK5TM Noise Eliminator: Click this link

Now on to the interesting stuff, I started this on Saturday and kept on it until 2am Sunday - I wasn't going to quit until it was finished.
Here are a couple of videos showing the results followed by some pictures - thats the lot, work it out for yourself, you are all clever people, however any questions just ask on the forum here and if you want to buy one contact terry VK5TM or use his article to make your own, if you want to use my design ask me and I will provide the Eagle CAD artwork free of charge without warranty.

Test 1: Click to watch Video

Test 2: Click to watch Video

Test 3: Click to watch Video
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